Flashcards in Heavy Machine Guns Deck (96):
The Browning machine gun caliber .50 HB, M2 is a
belt-fed, recoil-operated, air-cooled, crew-served machine gun.
The gun is capable of
single shot, as well as automatic fire, and operates on the short recoil principle.
The machinegun is capable of being fed from
either the right or left by repositioning certain parts
The M2 .50 caliber machine gun has a leaf-type
rear sight, graduated in both yards and mils. The scale ranges from 100 to 2,600 in yards and from 0 to 62 in mils.
The windage knob permits
deflection changes to right or left of center
the M2 .50 caliber machine gun reciever, barrel and tripod weigh a total of
the M2 .50 caliber machine gun reciever with barrel installed is how long
for the M2 .50 caliber machine gun rates of sustained fire are
Less than 40 rounds per minute (rpm)
for the M2 .50 caliber machine gun rates of rapid fire are
40 or more rpm
for the M2 .50 caliber machine gun rates of cyclic fire are
Maximum range for the M2 .50 caliber machine gun
Maximum Effective range for the M2 .50 caliber machine gun is
Grazing fire range for the M2 .50 caliber machine gun is
M2 – Dummy ammunition Characteristics are
Holes in cartridge
M2 .50 Caliber Machine Gun Ammunition types are
M2 – Dummy
M1, M1A1 – Blank
M2, M33 – Ball
M1, M10, M17 – Tracer
M1, M23 – Incendiary
M2 – Armor piercing
M8 – Armor-piercing incendiary
M20 – Armor-piercing incendiary-tracer
M903 – Sabot light armor penetrator
M962 – Sabot light armor penetrator-tracer
M1, M1A1 – Blank characteristics are
No bullet, crimped cartridge
M2, M33 – Ball characteristics are
M1, M10, M17 – Tracer characteristics are
Red, orange, or brown tip
M1, M23 – Incendiary characteristics are
M2 – Armor piercing characteristics are
M8 – Armor-piercing incendiary characteristics are
M20 – Armor-piercing incendiary-tracer characteristics are
Aluminum tip with red ring
M903 – Sabot light armor penetrator characteristics are
Amber tinted round
M962 – Sabot light armor penetrator-tracer characteristics are
Red tinted round
The purpose of the Barrel group on the M2 .50 Caliber Machine Gun is
Houses cartridges for firing
M2 .50 Cal Carrier assemblys purpose is
Provides handle to:
Remove barrel from the receiver
he purpose of Backplate group on M2 .50 Cal is
Bolt latch releases lock
Buffer tube sleeve
Left and right spade grips
The purpose of the Cover group on the M2 .50 Cal is
Feeds linked belt ammunition
Positions and holds cartridges in
position for extracting, feeding, and
The purpose of the Bolt group on the M2 .50 Cal is
Provides feeding, chambering, firing,
and extracting, using the propellant
gases and recoil spring for power
the purpose of the Receiver group of the M2 .50 Cal is
Serves as support for all major components
Houses action of weapon, which controls functioning of weapon
The purpose of the Bolt stud on the M2 .50 Cal is
Provides a means to move the bolt to the rear with the retracting slide handle
The purpose of the Barrel extension group of the M2 .50 Cal is
Secures the barrel to the recoiling parts
The purpose of the Barrel buffer body on the M2 .50 Cal is
Assists in recoil and counter-recoil of the bolt group
The purpose of the Driving spring rod assembly for the M2 .50 Cal is
Drives the bolt forward when the bolt latch release is depressed
The M2 .50 caliber machine gun has no
Condition 1 for the M2 .50 caliber machine gun is
A round in the chamber
This condition is also referred to as full load
Condition 2 of the M2 .50 caliber machine gun is
Bolt forward on an empty chamber
Rounds all the way against the cartridge stop
This condition is also referred to as half load
Condition 3 of the M2 .50 caliber machine gun is
Bolt forward on an empty chamber
Rounds inserted and held in place by the belt feeding pawl
Condition 4 of the M2 .50 caliber machine gun is
Bolt forward on an empty chamber
No source of ammunition
3 steps in Unloading & Clearing the M2 .50 Cal are
Ensure the barrel is cold. If hot (150 rounds in 2 minutes or less), let the weapon sit for 15 minutes.
Place weapon in single shot mode. Lock the bolt to the rear by pulling the retracting slide handle to the rear while maintaining positive control.
Open the top cover and remove the source of ammunition. Inspect the chamber to ensure it is clear.
steps to execute "LOAD" taking the M2 .50 caliber machine gun from condition 4 to condition 2 are
Point the weapon in a safe direction. Ensure weapon is in single shot mode.
Ensure the weapon is in condition 4:
No rounds inserted anywhere in the weapon
An empty chamber
Raise cover, lift extractor ejector, and slightly pull bolt to the rear.
Insert the double loop end of the belt in the feedway until the rounds meet the cartridge stop and place the extractor ejector between the first and second rounds. Close cover. Weapon is now half-loaded.
the steps to execute "MAKE READY" taking the M2 .50 caliber machine gun from condition 2 to condition 1 are
Point the weapon in a safe direction.
Ensure the bolt latch release is locked down. Ensure the weapon is on automatic.
Pull the retracting slide handle to the rear and release it.
CAUTION: The weapon is fully loaded.
the steps to execute "UNLOAD/CLEAR GUN" taking the M2 .50 caliber machine gun to condition 4 are
Ensure the barrel is cold. If hot (150 rounds in 2 minutes or less), let the weapon sit for 15 minutes.
Point the weapon in a safe direction and ensure weapon is in single shot mode
Unlock the bolt latch release.
Raise the cover.
Remove the ammunition from the feedway.
Pull the retracting slide handle to the rear until it locks.
Examine the chamber and T-slot to ensure they are clear of ammunition.
Insert a cleaning rod in the muzzle end of the barrel and push it through the bore until it can be seen in the receiver ensuring that the weapon is clear.
Return the retracting slide handle forward and depress the bolt latch release sending the bolt forward. Close the cover.
Malfunctions of the M2 .50 Cal are
Failure to function freely
Uncontrolled Automatic Fire
Failure to function freely is
Sluggish operation is usually due to human failure to eliminate excessive friction caused by
o Lack of proper lubrication
o Burred parts
o Incorrect headspace adjustment
o Incorrect timing
Uncontrolled Automatic Fire is
(runaway gun) is when fire continues even when the trigger or trigger control mechanism is released. If the cause is present before the gun is fired, the gun will start to fire when the recoiling groups move into battery the second time.
A runaway gun may be caused by
o A bent trigger lever, forward end of the trigger lever sprung downward
o Burred beveled contacting surfaces of the trigger lever and sear
o A jammed or broken side-plate trigger
To stop the uncontrolled automatic fire you should
o Keep the gun laid on target.
o Twist the belt, causing the gun to jam.
CAUTION: Do not unlatch the cover.
Wait 15 minutes to guard against cook off.
Replace broken, worn, or burred parts.
Check the side-plate trigger and trigger control mechanism, when applicable.
A stoppage is
any interruption in the cycle of operation caused by the faulty action of the gun or ammunition
Types of stoppages are
Failure to Feed
Failure to Chamber
Failure to Lock
Failure to Fire
Failure to Unlock
Failure to Extract
Failure to Eject
Failure to Cock
Immediate action is
the prompt action taken by the gunner without investigating the cause. The gunner performs immediate action; however, every crewmember must be trained to apply immediate action.
the steps to follow to reduce most stoppages without analyzing their cause in detail are
Yell, “Misfire!” to inform the gun line that you have a stoppage or malfunction.
Wait 5 seconds for the possibility of a hang fire.
Within the next 5 seconds, pull the bolt to the rear and watch for feeding and ejecting.
If feeding and ejecting occur, aim in and attempt to fire. If weapon
Fires continue mission.
Fails to fire, determine whether or not you have a hot barrel. If so, wait 15 minutes for barrel to reach air temperature.
NOTE: You have a hot barrel if it has fired 150 rounds or more in 2 minutes or less.
Once the barrel cools, proceed to remedial action
Remedial action is
the detailed examination of the weapon and ammunition to determine the cause of the stoppage
Removal of a cartridge from the T-Slot If the cartridge does not fall out during immediate action is
Put the weapon on single shot and pull the bolt to the rear.
Hold the bolt to the rear
With the extractor raised, use a cleaning rod to push the cartridge out the bottom of the receiver, or reach under the gun and push the round up out of the T-slot
To Remove a ruptured cartridge you
Raise the cover and pull the bolt to the rear.
Place the ruptured cartridge extractor in the T-slot of the bolt in the same manner as that of a cartridge, so that it is held in line with the bore by the ejector of the extractor assembly of the gun.
With the extractor aligned with the bore and held firmly in the T-slot, let the bolt go forward into the ruptured case; the shoulders will spring out in front of the case.
Pull the bolt to the rear and remove the ruptured case and extractor.
Disassembly of the M2 .50 Cal consists of
removing the major groups
and assemblies for inspection and cleaning
the eight major groups that must be disassembled in the order they should be removed for the M2 .50 Cal are
1 Barrell Group
2 Back-Plate Group
3 Driving Spring Rod Assembly
4 Bolt Group
5 Barrel Extension
6 Barrel Buffer Assembly
7 Barrel Buffer Assembly
8 Receiver Group
Function Check steps are
Place the weapon in the single-shot mode.
With the cover closed, lock the bolt to the rear (bolt should stay to rear while in the single-shot mode).
Return retracting slide handles to full forward position and press the bolt latch release.
Press down on the trigger; weapon should fire. (Check T-slot to ensure that firing pin does protrude.) Open the cover.
Place the weapon in the automatic-fire mode.
Pull the retractor slide handle to the rear and release. (Bolt should not lock to rear.)
Make sure firing pin does not protrude.
Press trigger; weapon should fire.
Make sure firing pin does protrude.
Disassemble, clean, and oil the gun in a clean, dry location. If possible, when not in use, keep the gun covered with a
o Gun cover
What do you use to clean the machine gun
Use CLP to clean the machine gun. As its name implies, it cleans, lubricates, and preserves all in one application. After cleaning the gun with CLP, wipe it dry and reapply a thin coating
Rifle bore cleaner (RBC) is a
cleaning solvent, which can be used to clean powder residue, carbon, and dirt from weapons. RBC does not preserve or lubricate a weapon
Use RBC and oil only when CLP is not available
When you inspect the machine gun, it should
be completely disassembled. Look for dirt, cracks, burrs, and rust
When inspecting the barrel check for
Be sure that the bore and chamber are:
Free of rust
When inspecting the moving parts check for
Be sure moving parts are clean and lightly oiled.
Operate the retracting slide handle and bolt latch release several times to see that the parts function without excessive friction.
When inspecting Headspace and timing check for
Using the gauges, check to ensure that headspace and timing are correct.
When inspecting Rear sight and windage knob check for
Be sure the sight:
Is in good condition
Free of grease or dirt
Elevation is set at 1000
Windage is set at zero
The sight is down
When inspecting Mount (M3, MK64, M36, or M4) check for
Be sure that the mount
Is clean and lightly lubricated
Be sure all clamps are securely tightened
When inspecting Spare parts and tools check for
Be sure spare parts are clean and lightly oiled
Be sure spare parts kits are complete and in good condition.
Requisition replacement parts.
Examine newly drawn parts.
When inspecting T&E check for
Be sure it is clean and lightly lubricated.
Be sure both hand wheels work properly.
When inspecting Ammunition check for
Be sure ammunition is properly stored. Ensure boxes and ammunition are in good condition and not oiled.
Machine Gun Headspace is
the distance between the face of the bolt and the base of the cartridge case, fully seated in the chamber
Machine Gun Timing is
the adjustment of the gun so that firing takes place when the recoiling parts are in the correct position for firing
When to Check and set headspace
o Before firing
o After assembling the gun
o After replacing the barrel or receiver group
Steps to set Machine gun timing are
Check headspace first as previously described.
Pull the bolt to the rear with the retracting slide handle and release to cock the machine gun.
Grasp the retracting slide handle and retract the bolt just enough (1/16-inch) to insert the no-fire gauge between the barrel extension and the trunnion block. Release the retracting slide handle
Depress the trigger; gun should not fire. NOTE: If the gun
Does not fire, go to step 5.
Does fire, you have early timing. Go to steps 7 through 14
Grasp the retracting slide handle and retract the bolt just enough to remove the no-fire gauge and insert the fire gauge in the same place. Release the retracting slide handle.
Depress the trigger; gun should fire. If it:
Does, timing adjustment is now complete.
Does not fire, you have late timing. Go to steps 7 through 14.
Remove the gauge, cock the gun, and return the bolt forward.
Insert the fire gauge.
Remove the backplate.
NOTE: Weapon must be in single-shot mode to remove backplate. Always place the backplate on the ground with the spade handles down to avoid damaging the trigger mechanism.
Screw the timing adjustment nut all the way down until it touches the trigger lever (see diagram below).
NOTE: The timing nut will come off the timing post if it is depressed too many clicks. If this happens, apply upward pressure to the timing nut while screwing it back on to the timing post.
Try to fire the machine gun by pushing up on the rear of the trigger lever located directly underneath the timing nut; gun should not fire.
Screw the timing adjustment nut up (to the right) one click at a time. Push up on the trigger lever after each click. Keep doing this until the gun fires.
NOTE: You must apply firm pressure to the trigger lever.
Turn the timing adjustment nut an additional two clicks to compensate for heat expansion.
Replace the backplate, remove the gauge, and cock the machine gun.
Repeat steps 3 through 6 to ensure timing is set correctly.
M2 .50 Caliber Machine Gun Cycle of Operations consists of what basic steps
Feeding - The act of placing a cartridge in the receiver, approximately in back
of the barrel, ready for chambering.
Chambering - Placing the cartridge into the chamber of the weapon.
Locking - The bolt is locked to the barrel and barrel extension.
Firing - The firing pin is released, igniting the primer of the cartridge.
Unlocking - The bolt is unlocked from the barrel and barrel extension.
Extracting - The empty cartridge case is pulled from the chamber.
Ejecting - The empty cartridge case is expelled from the receiver.
Cocking - The firing pin is withdrawn into the cocked position.
The M3 mount is a
folding tripod with three, telescopic, tubular legs connected at the tripod head
The T&E mechanism is used to
engage preselected target areas at night or during limited visibility conditions
A pintle connects
the gun to the tripod mount, M3
The truck mount, M36 consists of
a cradle with a roller carriage on a circular track
The MK64 gun cradle mount is a
vehicle mount primarily designed for the M2. However, because of its versatility, the MK64 will accept the MK19 also (using the M2 mounting adapter assembly). The MK64 is used when mounting the gun on a HMMWV.
The MK19 is a
belt-fed, air-cooled, blowback-operated, crew-served, fully automatic 40 mm grenade launcher
What must you do first before you disassemble the MK19
Clear the weapon
What is the sustained rate of fire for the MK19
40 rpm (3-5 round bursts
Where is the weapon safety located
On the sear assembly at the bottom rear of the receiver assembly
What is condition 1 for the MK19
Rounds inserted all the way to the round positioning block
Bolt to the rear
Round on the face of the bolt
Weapon on safe
When closing the top cover, in what position must the feed slide assembly be; and in what position must the bolt be to ensure proper alignment of the primary and secondary drive levers
How much armor plating, in inches, is the weapon capable of penetrating, when firing ammunition at zero degree obliquity
Within how many meters must the 40-mm HE round impact to cause casualties to exposed enemy personnel
To stop a runaway weapon, what step(s) must be taken
Unlock and lower one charging handle while keeping control of the weapon
What is condition 3 for the MK19
Rounds inserted past the primary feed pawl, bolt forward, no rounds on its face, weapon on safe
If a stoppage occurs, how long must you wait before pulling the bolt to the rear
How many rounds per burst should the gunner fire when engaging targets at the sustained rate?
3 to 5
What is the maximum effective range of the MK19
Which tripod is used with the MK19
True or False
When loading the weapon, place the female link end of the ammunition belt through the feed throat and draw the ammunition into the weapon feed area